From time to time in the past there have been many efforts at the development of antigens for use in therapeutic treatments for the immunization of animals of the mammalian and avian orders. These antigens develop an immune response within the animal that may effectively function therapeutically with regard to certain disease disorders. For example, U.S. Pat. No. 3,479,430 deals with immunizing porcine animals against transmissible gastroenteritis by injecting into the pregnant sow before farrowing a vaccine of attenuated transmittible gastroenteritis virus. Other antigen type products have been developed for canine corona vaccine, for porcine atrophic rhinitis, and for porcine rotavirus.
The ability of these antigen based medicinals to properly develop the desired immune response in the animal is in part based upon the effect of the adjuvant employed with the vaccine. Put another way, the precise means by which the antigen is presented can either distract from the activity, or enhance the activity, in terms of developing the desired immune response.
In the past there have been many adjuvants used, see for example Reynolds et al., "Adjuvant Activity of a Novel Metabolizable Lipid Emulsion with Inactivated Viral Vaccines,"Infection and Immunity, June 1980 pp. 397-943, which discusses such adjuvants as glycerine, glycerine in combination with lecithin, Freund adjuvant, and others.
The use of adjuvants in combination with antigens is not a new or unique method of enhancing immunization in animals. In 1926, Glenny, et al. reported that the addition of potassium alum to diptheria toxoid resulted in the formation of a precipitate that bound the toxoid, Glenny, A.T., et al., Toxoid Precipitated with Alum., J. Path. Bacteriol. 34:267-75, 1931. The precipitate, when resuspended in water was shown to be enhanced in its ability to produce immunity over the original toxoid from which it was produced.
Further, the use of oil-based adjuvants is not new or unique. Such use appeared in the literature as early as 1916 when Le Moignac and Pinoy of France emulsified a suspension of Salmonella typhimurium in liquid paraffin (mineral oil) by using lanolin as an emulsifier and obtained an improved immune response in injected animals.
Other reports of various oil combinations incorporated as adjuvants appeared in the literature between 1935 and 1943, McKercher, et al., A review of the current status of oil adjuvants in foot-and-mouth disease vaccines, Dev. Biol. Stand. 35:107-12, 1977. These included the use of oil adjuvants in vaccines for bovine pleuropneumonia, brucellosis and anthrax of cattles.
In the early 1900's Freund combined paraffin (mineral oil) with whole killed tubercle bacilli as an adjuvant (Freund's Complete Adjuvant or FCA) for enhancing the immunologic response in various experimental animals with considerable success. This led to later studies using an extract of the tubercle bacillus, instead of whole bacteria, combined with the oil adjuvant. The term Freund's Incomplete Adjuvant (FIA) came from these later studies and is commonly used today. While effective as adjuvants when combined with a variety of antigens, unfortunately, both FCA and FIA which are oil-based adjuvants, are much too irritating for routine use as adjuvants in commercially produced biological products for use in the mammalian and avian species of animals.
In 1979, Munder, P.G. et al., reported on the immunomodulating and other biological effects of the phospholipid, lysophosphatidylcholine (Lysolecithin). The report dealt primarily with the ability of Lysolecithin, as a surface active agent, to alter cell membranes in such a way as to facilitate cell interactions, activate synthesis of regulatory molecules, or even function as analogs of naturally occurring regulatory molecules, Nervig, R.M., Advances in Carriers and Adjuvants for Veterinary Biologics, Iowa State University Press, p. 17, 1986. Its potential role as an "antigen presenter" was not addressed.
It is a primary object of the present invention to provide an improved adjuvant which can be used for the immunization of animals of the mammalian and avian orders for administration of antigens in an manner which substantially improves the antigen from the standpoint of reducing the amount of irritation, and from the standpoint of enhancing the effectiveness of the desired immunization response.
The method of accomplishing the above primary objective as well as others will become apparent from the detailed description of the invention which will follow hereinafter.